Speaker
Dr
Hiroshi Matsumura
(KEK)
Description
A 12-MeV cyclotron used for production of radiopharmaceuticals for positron-emission tomography (PET) at the Medical and Pharmacological Research Center Foundation in Hakui, Ishikawa, Japan was decommissioned in March 2015. The decommissioning work began immediately, and the entire cyclotron body and its accessories were removed from the cyclotron room. Currently, a method for measuring the specific activity distribution in all concrete walls of the cyclotron room is required in order to identify the contaminated part. Therefore, in this study, an in-situ specific-activity determination method was developed.
Summary
In January 2017, gamma rays from the activated concrete walls of the cyclotron room were measured in situ at 20 locations using a portable Ge-detector with a lateral 6.5-cm-thick Pb-shield touching the concrete wall surface. The specific activities of five radionuclides produced by nuclear reactions during the cyclotron operation were determined. The specific activities obtained in situ agreed well with those obtained by off-site measurement for sampled concretes. Further, surface dose rates were measured using a NaI scintillation counter at the same locations. A calibration curve from a contact dose rate to a specific activity was obtained, and this enabled easy in-situ specific activity determination using a NaI scintillation counter.
Primary author
Dr
Hiroshi Matsumura
(KEK)
Co-authors
Mr
Akihiro Toyoda
(KEK)
Mr
Hiroyuki Sasaki
(Japan Environment Research Co., Ltd.)
Mr
Kazuhiro Matsumura
(Japan Environment Research Co., Ltd.)
Prof.
Kazuyoshi Masumoto
(KEK)
Mr
Takayuki Nakabayashi
(Japan Environment Research Co., Ltd.)
Mr
Toshiyuki Yagishita
(Japan Environment Research Co., Ltd.)
Mr
Yoshiyuki Yamaya
(Japan Environment Research Co., Ltd.)
